|
I used weather stripping adhesive to glue the edge of the cone back on the frame. It works really well. I used the same on the holes in the cone, but there was only one big hole previously glued and 3 small ones. Other than that the cone is in great shape and i see no reason to get it reconed. Now that it's glued down I can see how stiff the cone is, as it doesn't flex that much at all. too much pressure will puncture it. The speaker is electrodynamic so the field coil provides the magnet for the speaker. The field coil has a resistance of 1.06k which I can find a replacement easy. I don't want to use a resistor because it won't filter that well. A Hammond 155J should do the trick; 1.026k ohm ,30mA max, 400VDC max, 15H. I can also use the an audio transformer by Hammond that has multiple output terminals for connecting almost any speaker you want, just use the right terminals to get the proper impedance. But I really don't want to do that because I want to keep everything as original as possible. The .005uF bypass capacitor from the cathode to the plate is required, but possibly the value can be changed to pass everything below 20kHz. It should have a low reactance at audio frequencies. At 20kHz the reactance is 1.5k ohms. Think I can change it without issue?
As for the trimmer capacitor, like you suggested, I'm going to tune to the strongest station and adjust the trimmer for the best signal.
Thanks.
Jonathan
|